Centrifugal gas compressor



Jan. 9, 1968 Filed Sept. 6, 1966 2 Shets-Sheet 1 INVENTOR JAMES w.-ENDRESS..

ATTORNEY.

Jan. 9, 1968 J. w. ENDRESS 3,362,625

' CENTRIFUGAL GAS COMPRESSOR Filed Sept. 6. 1966 2 Sheets-Sheet FIG. 3

t--- l JJ JJ' jl l 2; v INVENTQR.

-. JAMES W. ENDRESS.

ATTORNEY.

United States Patent 3,362,625 CENTRIFUGAL GAS COMPRESSOR James W.Endress, Syracuse, N.Y., assignor to Carrier Corporation, Syracuse,N.Y., a corporation of Delaware Filed Sept. 6, 1966, Ser. No. 577,447 4Claims. (Cl. 230-114) ABSTRACT OF THE DISCLOSURE A centrifugalcompressor capable of stable operation under low volumetric flow rates.An annular ring, rotatable about the axis of the compressor is operablyconnected to inlet guide vanes and a diffuser restriction ring toprovide programmed restriction of the inlet and diffuser passages inrelation to the compressor loading.

This invention relates to gas compression equipment. More particularly,this invention relates to centrifugal gas compressors. Still moreparticularly, this invention relates to centrifugal gas compressorssubjected to large load variations.

One of the major problems arising in the use of centrifugal gascompressors for applications where the compression load varies over awide range is flow stabilization through the compressor. The compressorinlet, impeller and diffuser passage must be sized to provide for themaximum volumetric flow rate desired. When there is a low volumetricflow rate through such a compressor, the flow becomes unstable. As thevolumetric flow rate is decreased from a stable range, a range ofslightly unstable flow is entered. In this range, there appears to be apartial reversal of flow in the diffuser passage creating noises andlowering the compressor efficiency. Below this range, the compressorenters what is known as surge, wherein there are periodic complete flowreversals in the diffuser passage, destroying the efficiency of themachine and endangering the integrity of the machine elements. Since awide range of volumetric flow rates is desirable in many compressorapplications, numerous modifications have been suggested to improve flowstability at low volumetric flow rates. One of the most accepted andsuccessful modifications has been the addition of guide v'anes in theinlet of the compressor to vary the flow direction and quantity ofentering gas. However, since the instability at low flow rates is alsorelated to the diffuser configuration, it would appear desirable to varydiffuser configuration in response to the load on the machine to providea more flexible compressor.

It is therefore the chief object of this invention to provide a methodof varying the capacity of a centrifugal compressor to provide a largerange of stable flow rates.

It is another object of this invention to provide a centrifugal gascompressor having means therein to stabilize the gas flow therethroughat extremely low flow rates.

It is a further object of this invention to provide means forautomatically interrelating inlet guide vane movement with movement ofdiffuser flow restriction means to optimize compressor efficiency over awide range of flow rates.

The objects of this invention are attained by providing a centrifugalgas compressor with inlet guide vanes and diffuser restriction means. Anannular control member, arranged for movement in a circular path,simultaneously effects the position of the inlet guide vanes and thediffuser restriction means to provide peak efiiciency at any flow rate.

Other objects and features of my invention will be apparent upon aconsideration of the ensuing specification and drawings in which:

FIGURE 1 is an elevational view, partly in section of a portion of acentrifugal compressor including the impeller, inlet guide vanes, anddiffuser passage, the compressor incorporating my invention.

FIGURE 2 is a view taken along line II-II of FIG- URE 1.

FIGURE 3 is a fragmentary elevational view, partly in section of thecompressor in FIGURE 1, further illustrating the guide vane and diffuserrestriction actuator means of my invention.

Referring more particularly to the drawing, there is shown a gascompressor 1 of the well-known centrifugal type wherein gas to becompressed is induced to flow in an axial direction into a vanedimpeller connected to a suitable drive for imparting rotary motionthereto. As the gas is compressed during its travel through thecompressor, it is directed radially from the impeller to a diffuserpassage communicating with the tip of the impeller. The compressorincludes a housing 2 with inlet passage 3 and diffuser passage 5. Only aportion of the housing is shown, it being understood that such aconstruction is conventional in equipment of the kind underconsideration. An impeller 7, affixed to shaft 9 by nut 11 is providedin housing 2 between the inlet passage 3 and diffuser passage 5. Inletguide vanes 13 journaled for rotation in housing 2 are positioned aboutthe inlet passage to control the direction and quantity of gas flowtherethrough. An annular control member 15 is mounted on balls 17 instationary race 19 for movement in a circular path. A plurality of camtracks 21 equally spaced circumferentially of annular control member 15are provided for mating engagement with cam followers 23. Cam followers23 are comprised of rollers 25 bolted on push rods 27. Push rods 27 arebolted to diffuser restriction ring 29 so that rotation of annualcontrol member 15 will effect axial movement of diffuser restrictionring 29 within diffuser passage 5, note the position indicated in dottedlines, said movement conforming to the shape and size of the tracks 21.

Arms 31, on guide vanes 13 are connected to annular control member 15 bylinks 33 so that rotation of annular control member 15 will also effectrotation of guide vanes 13.

A control rod 35 is mounted for rotation about its longitudinal axis torotate annular control member 15 by means of links 37 and 39 pivotallymounted therehetween. The control rod 35 can be rotated by anywell-known means (not shown) such as electric, pneumatic or hydraulicpositioners responsive to an operating condition of the compressor orits associated equipment which is indicative of the load on thecompressr. Thus if the compressor were to be used in a refrigerationmachine, the positioning means could be responsive to the temperature ofthe chilled water leaving the machine, this temperature being related tothe quantity of refrigerant being lifted from the low side to the highside of the machine by the compressor. If the compressor were being usedto compress air, the positioning means could be responsive to ambienttemperature since this is an indication of the air density and thereforethe quantity of air being compressed.

As can be seen in FIGURE 3, cam tracks 21 have a specializedconfiguration. The track is so designed that rotation of annular controlmember 15 will rotate the guide vanes from full open position to a 60%closed position without restricting diffuser passage 5. If a reductionin flow greater than that caused by the guide vanes in the 60% closedposition is desired, further rotation of annular control member 15 willsimultaneously move guide vanes 13 between 60% closed and closed andmove diffuser restriction ring to provide a diffuser capacity betweenand 5% of maximum. If a greater reduction than this is desired, furtherrotation of annular control member 15 will hold the diffuser restrictionring 3 in the 5% diffuser capacity position and move guide vanes 13between 85% and 100% closed. By correlating guide vane movement anddiffuser restriction ring movement in the manner described above, thelift capacity of the compressor is maximized over the complete range offiow rates attainable.

While I have described a preferred embodiment of my invention, it is tobe understood that my invention is not limited thereto, but may beotherwise embodied within the scope of the following claims.

I claim:

1. A centrifugal gas compressor comprising, a housing having an inletpassage and a diffuser passage formed therein, an impeller mounted insaid housing between the inlet and diffuser thereof, a plurality ofguide vanes pivotally mounted in the housing to vary the quantity of gasflowing through the inlet passage, diffuser restriction means includingan annular diffuser member mounted for axial movement across thediffuser passage to restrict fiow of gas therethrough, actuator meansincluding an annular control member arranged for movement in a circularpath about the inlet passage connected to said guide vanes andregulating means effective in response to and operable only after apredetermining movement of the annular control member and pivoting ofsaid guide vanes for axially positioning said annular diffuser member inresponse to further movement of said annular control member.

2. A centrifugal gas compressor according to claim 1 wherein saidregulating means includes a plurality of cam followers attached to saiddiffuser restriction means, said annular control member having aplurality of cam tracks formed therein for engagement by said camfollowers to move said diffuser restriction means in response to thecircular movement of said annular control member.

3. A centrifugal compressor according to claim 1 wherein said actuatormeans further includes guide vane linkage between said annular controlmember and said guide vanes, said guide vane linkage means comprisingarms, affixed to said guide vanes for rotation therewith, and, linkingrods, pivotally connected to said annular control member and said armsto rotate said guide vanes when said annular control member is rotated.

4. A centrifugal compressor according to claim 1 wherein said actuatormeans further includes a control rod mounted in said housing forrotation therein, and, control rodlinkage means, operably associatedwith said annular control member so that rotation of said control rodeffects rotation of said annular control member.

References Cited UNITED STATES PATENTS 2,645,410 7/1953 Bauger et al230-114 3,032,259 5/1962 Jassniker 230-114 3,251,539 5/1966 Wolfe et al.230115 3,289,919 12/1966 Wood 230-127 FOREIGN PATENTS 845,156 7/ 1952Germany.

0 HENRY F. RADUAZO, Primary Examiner.

DONLEY I. STOCKING, Examiner.

